Such frames form the mechanical interface between the drive and the machine connected to this drive. Since it is frequently useful to prevent an input of heat into the machine, cooling of the drive at this interface is especially expedient.
Electric drives, especially synchronous drives, which are able to be directly connected to the application without mechanical transformation, are described in U.S. Pat. No. 5,642,013. Here, using mainly the example of linear motors, it is illustrated how such drives can be designed in order to avoid detent torques, or to at least reduce them markedly. To cool these engines (which are able to generate a force or a torque even at standstill and thus without the cooling effect of moving air), cooling ducts between the teeth of the iron core accommodating coils are suggested in this instance. However, such cooling ducts reduce the filling factor of the interspaces of the teeth, so that the engines are ultimately less powerful than those having more windings per coil. In FIG. 15 of U.S. Pat. No. 5,642,013, a rotary synchronous motor is shown as well. Example embodiments of the present invention are particularly suitable for engines of this type. As far as the details of such an electric drive are concerned, U.S. Pat. No. 5,642,013 is expressly incorporated herein in its entirety by reference thereto.
European Patent No. 0 868 012 also describes a linear synchronous motor, which, however, is cooled from the rear side of the laminated core, i.e., from the side lying across from the teeth and coils. Toward that end, the iron core cast in epoxy resin sits in an actively cooled frame made of metal, on whose rear side, i.e., facing away from the teeth and coils of the iron core, cooling ducts extend. In an exemplary embodiment, the intake and outlet for the coolant are arranged next to each other at the same end of the linear motor. A meander-shaped cooling duct makes its way toward the opposite located end of the linear motor and back again from there, so that the cooling effect is evenly distributed across the entire length of the engine. However, such meander-shaped cooling ducts are very difficult to produce during the machining due to the frequent changes in direction, and they cause a considerable pressure drop because of their significant length.